The invention is directed to a method, as well as, to arrangements for the operation of a gas discharge lamp provided with heater coils, particularly a fluorescent lamp, whereby a high-frequency ac voltage for operation of the lamp is generated by an inverter from a dc voltage which may be derived from a line ac voltage by rectification. The lamp is arranged parallel to the capacitance of a series-resonant circuit formed of a capacitor and of an inductor which includes the heater coils of the lamp, and whereby, during the heating-up operation of the heater coils (starting interval phase) between the time the power supply is turned on and the lamp is ignited, the voltage applied thereto is limited to a value below its ignition voltage.
Gas discharge lamps requiring a warm start which, upon employment of an electronic ballast, are operated with the high-frequency output voltage of an inverter are generally known. It is thereby important that the voltage appearing at the lamp when the power supply is turned on does not reach the ignition voltage value until the heater coils of the lamp have been adequately heated.
For example, such a warm start gas discharge lamp is disclosed by the reference, European patent specification No. 0 059 064. As disclosed therein, the frequency of the inverter, given the assistance of a control means for turning the supply voltage on, initially operates at a frequency above the resonant frequency of the series-resonant circuit and, toward the end of the starting interval phase, reduces the frequency of the inverter in the direction toward the resonance of the series-resonant circuit such that the voltage at the lamp rises, causing the lamp to ignite.